How do you classify a K1 Fiancé(e) Visa? Is it a Nonimmigrant or an Immigrant Visa?

The K1 Fiancé(e) Visa is defined by USCIS as:

The K-visa categories for fiancé(e)s of U.S. citizens and their accompanying minor children (K-1 and K-2 visas) were created to speed up the immigration process for such individuals so they could travel more quickly to the United States.

By allowing a fiancé(e) and his/her accompanying minor children to be admitted to the United States as nonimmigrants, fiancé(e)s can be spared a long separation from their intended spouse, while continuing their processing for an immigrant visa after the marriage takes place.

From: USCIS.gov | K Nonimmigrant

Yes. It is confusing at first. To simplify, a K1 Fiancé(e) Visa is technically a Nonimmigrant Visa but has Immigrant intent. The “Immigrant” part doesn’t kick in until you marry your U.S. Citizen fiancé and apply for Adjustment of Status (AOS).

Though it may be a Nonimmigrant Visa, the Immigrant Visa Unit at the U.S. Embassy handles it for the purpose of the previously mentioned intent to immigrate.